1681993881653 has 4 divisors (see below), whose sum is σ = 1682212585728. Its totient is φ = 1681775177580.

The previous prime is 1681993881643. The next prime is 1681993881671. The reversal of 1681993881653 is 3561883991861.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 1681993881653 - 2⁴ = 1681993881637 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1681993881643) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 109340501 + ... + 109355882.

It is an arithmetic number, because the mean of its divisors is an integer number (420553146432).

Almost surely, 2^{1681993881653} is an apocalyptic number.

It is an amenable number.

1681993881653 is a deficient number, since it is larger than the sum of its proper divisors (218704075).

1681993881653 is an equidigital number, since it uses as much as digits as its factorization.

1681993881653 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 218704074.

The product of its digits is 67184640, while the sum is 68.

The spelling of 1681993881653 in words is "one trillion, six hundred eighty-one billion, nine hundred ninety-three million, eight hundred eighty-one thousand, six hundred fifty-three".